/Engine/Source/Runtime/HeadMountedDisplay/Public/IXRTrackingSystem.h
Refreshes the system's known tracking-to-world transform. Helpful for clients if they change the world's representation of the XR origin, or if they want to override the system calculated transform - calling this will update the known transform returned byGetTrackingToWorldTransform().
void UpdateTrackingToWorldTransform ( const FTransform & TrackingToWorldOverride )